Coexpression of two distinct muscle acetylcholine receptor alpha-subunits during development.
The nicotinic acetylcholine receptor is a ligand-gated channel that mediates signalling at the vertebrate neuromuscular junction. It is a pentameric complex of four different subunits, assembled with a stoichiometry of alpha 2 beta gamma delta. Muscle-like alpha-subunits have been cloned from Torpedo, mouse, calf, rat, chicken, human and Xenopus, and only a single alpha-subunit complementary DNA from each species has been detected. We report here the cloning and characterization of a second muscle alpha-subunit cDNA from Xenopus, and show that this and a previously reported Xenopus alpha-subunit cDNA are encoded by distinct genes. The novel alpha-subunit reported here is expressed uniquely in oocytes; but both types of alpha-subunit are coexpressed throughout muscle development. This latter observation indicates that the expression of these two alpha-subunits is different from a previously reported developmental 'subunit-switch' mechanism used to generate channel diversity.
Hartman
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DS
Department of Biology, Yale University, New Haven, Connecticut 06511.
Claudio
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D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002645:Chickens; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D015870:Gene Expression; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D024510:Muscle Development; D009132:Muscles / Q000196:embryology / Q000378:metabolism; D009693:Nucleic Acid Hybridization; D051381:Rats; D011950:Receptors, Cholinergic / Q000235:genetics*; D015183:Restriction Mapping; D012260:Ribonucleases; D014101:Torpedo; D014981:Xenopus
D011950:Receptors, Cholinergic; D004247:DNA; D012260:Ribonucleases